In modern medicine there are numerous treatment situations in which it is desirable to create shunts or flow-through connections between blood vessels and/or other anatomical structures of the body. Such treatments include, for example, hemodialysis, hemotiltration, hemodiafiltration, plasmapheresis, and extracorporeal membrane oxygenation (ECMO). In many cases, open surgical techniques have been used to form anatomic connections or fistulas between adjacent vessels of body structures. More recently, percutaneous catheter-based techniques and devices have been developed for creating channels or passageway's (i.e., shunts) between adjacent vessels or anatomical structures.
In addition to the above-listed treatments, arteriovenous (AV) shunt devices have been proposed for treating chronic obstructive pulmonary disease (COPD) and drug-resistant hypertension. COPD, also called chronic obstructive airway disease, is a syndrome that may be caused by a number of different diseases, all of which damage the alveoli and bronchioles, leading to impaired lung function. These diseases include asthmatic bronchitis, chronic bronchitis (with normal airflow), chronic obstructive bronchitis, and emphysema. As the alveoli and bronchial tubes are destroyed, the remaining healthy lung tissue must work harder to provide the required amount of blood oxygenation. The need for more air leads to lung over-inflation. As the lung over-expands, it gradually enlarges, completely filling the chest cavity and causing a sense of shortness of breath. The lung eventually loses its elasticity and the combination of a larger, less elastic lung and damaged, nonfunctioning tissue leads to slower airflow into and out of the lung, resulting in the feeling in the patient of an obstructed airway.
One manner of treating COPD is oxygen therapy, which requires a patient to remain near a stationary oxygen source or carry a bulky portable oxygen source when away from home or a treatment facility. Understandably such oxygen therapy has many disadvantages. One surgical treatment that has been proposed for treating patients with COPD is lung reduction surgery. Such surgery, however, can be used on only a small percentage of the total patient population, requires long recovery times, and does not always provide a clear patient benefit.
Arteriovenous (AV) shunt devices for treating COPD provide a fistula between an artery and a vein that are anatomically parallel to each other. The approach is to create an arteriovenous fistula by implanting a shunt-like device between two major blood vessels in, for example, the leg, thus utilizing cardiovascular reserve to overcome respiratory insufficiency and improve oxygenation to the lungs. The shunt allows oxygen-rich blood from the artery to flow to the vein and thereby increases the oxygen content of the blood returning to the heart and lungs, which in turn is considered to benefit a patient suffering from COPD. The implantation of the shunt can increase cardiac output by about one liter per minute, without impacting heart rate or oxygen consumptions.
Such shunt devices have been suggested to be implanted via an open surgical procedure or via a minimally invasive intravascular catheterization procedure, depending on the specific arterial and venous locations that are to be connected by the AV shunt. A need continues to exist in the art for an AV shunt that may be quickly and simply delivered, deployed, and secured in place via a minimally invasive intravascular procedure. In addition, a need continues to exist in the art for an AV shunt that directs blood flow into and out of the fluid passageway of the shunt.